Synchronous transmission pivot shaft device

ABSTRACT

A synchronous transmission pivot shaft device has a simplified structure and less assembled components and reduces assembling tolerance/motional space. The synchronous transmission pivot shaft device includes an assembly of a main body, a first operation board and a second operation board disposed on the main body. The first operation board has an obliquely extending arm section. The second operation board has an obliquely extending arm section. The arm sections of the first and second operation boards are respectively received in a first oblique rail and a second oblique rail of the main body. When a user operates the first operation board or the second operation board to move, the first operation board or the arm section thereof and the second operation board or the arm section thereof respectively synchronously move along the first and second oblique rails to achieve opening/closing effect.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a pivot shaft structure, andmore particularly to a synchronous transmission pivot shaft device,which employs oblique arm sections and cooperative oblique rails toachieve synchronously moving effect. Also, the synchronous transmissionpivot shaft device has less assembled components and reduces assemblingtolerance/motional space.

2. Description of the Related Art

There are various electronic apparatuses provided with covers or displayscreens, such as mobile phones, notebooks, PDA and electronic books. Thecovers or display screens are pivotally mounted on the electronicapparatuses via pivot pins or rotary shafts, whereby the covers or thedisplay screens can be freely rotated and opened/closed under externalforce.

In order to operate the display module (such as the screen) and/or theapparatus body module of the electronic apparatus in more operationmodes to widen the application range thereof, a conventional dual-shaftmechanism mounted between the display module and the apparatus bodymodule has been developed to rotate the display module and/or theapparatus body module by different angles in accordance with differentoperation modes. For example, Taiwanese Patent No. 99211350 “dual-shafthinge device”, Taiwanese Patent No. 99225737 “biaxial hinge device” andU.S. Pat. No. 7,512,426 B2 “mobile communications device withsynchronizing hinge” disclose typical embodiments.

With respect to the operation, motion and structural design of suchdual-shaft mechanism or pivot shaft assembly, in order to achievesynchronous transmission effect, practically at least one set ofdual-shaft assembly in cooperation with the transmission mechanism mustbe used to make the display module and/or the apparatus body module movein different operation modes. For example, Taiwanese Patent No.102216086 “synchronous moving device applied to dual-shaft system” andTaiwanese Patent No. 105126016 “pivot shaft device with displaceableshaft” disclose typical embodiments.

The conventional dual-shaft mechanism includes an assembly of multiplerotary shafts, gears and link plates for transmitting power, whereby therotary shafts can synchronously rotate. In order to meet therequirements for lightweight and thin structure of the electronicapparatus, the rotary shafts and the relevant connection components andthe gears and link plates for transmitting power are as minified aspossible so that the electronic apparatus can have a simplifiedstructure and beautiful appearance.

However, as well known by those who are skilled in this field, theminimization of the gears and link plates will lead to reduction of theengagement/transmission working depth between these components. As aresult, the structural strength of the gears will be obviously weakenedand the use lifetime of the gears will be shortened. This isunbeneficial to the cooperation and power transmission between the gearsand often causes an idling travel due to rotational slippage. Also, theoperational hand feeling of a user will be deteriorated.

Especially, when a user operates the display module to rotate, themultiple gears and link plates are driven to drive the rotary shafts,whereby the apparatus body module is driven to synchronously rotate. Therotary shafts are assembled with the multiple gears and link plates fortransmitting power so that the structural relationship between thesecomponents is relatively complicated. These components are troublesometo assemble and the assembling tolerance is large. Also, thesecomponents have larger volume to occupy much room. This is not what weexpect.

To speak representatively, the conventional dual-shaft mechanism orpivot shaft and the relevant connection components thereof have someshortcomings in use and structural design. The rotary shaft structureand the relevant components can be redesigned to eliminate the aboveshortcomings in operation and change the use form as well as widen theapplication range. For example, in condition that the requirement forlightweight and thin design of the electronic apparatus is satisfied andthe pivot shaft device or the relevant components are such structurallydesigned as to synchronously move, the shortcoming of the conventionalstructure that the power transmission can be hardly smoothly performedto cause idling travel can be improved. In addition, the structural formof the dual-shaft system of the conventional pivot shaft device isomitted, whereby the display module and/or the apparatus body module canbe synchronously move in different operation modes. Moreover, the pivotshaft device can be assembled with the electronic apparatus at highertransmission precision and stability. Also, the structure and assemblingprocess are simplified and the shortcoming of the conventional structurethat the cooperative components have larger volume to occupy more(motional) space. None of the above references specifically teaches,suggests or discloses the above issues.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide asynchronous transmission pivot shaft device has a simplified structureand less assembled components and reduces assembling tolerance/motionalspace. The synchronous transmission pivot shaft device includes anassembly of a main body, a first operation board and a second operationboard disposed on the main body. The first operation board has anobliquely extending arm section. The second operation board has anobliquely extending arm section. The arm sections of the first andsecond operation boards are respectively received in a first obliquerail and a second oblique rail of the main body. When a user operatesthe first operation board or the second operation board to move, thefirst operation board or the arm section thereof and the secondoperation board or the arm section thereof respectively synchronously(or in reverse directions) move along the first and second oblique railsto achieve opening/closing effect. The synchronous transmission pivotshaft device of the present invention improves the shortcoming of theconventional dual-shaft pivot shaft device that the structure iscomplicated and it is troublesome to manufacture and assemble thecomponents and the assembling tolerance is large and the structure isunbeneficial to the power transmission to cause idling travel.

In the above synchronous transmission pivot shaft device, the main bodyis an arched cylindrical body having a chamber with an arched(cross-sectional) structure. Multiple restriction sections are disposedor integrally formed in the chamber to define the first and secondoblique rails.

In the above synchronous transmission pivot shaft device, the main bodyis disposed on a base seat. The base seat has a chamber for receivingthe main body. The main body is permitted to reciprocally move withinthe chamber of the base seat. When the first operation board or the armsection thereof moves along the first oblique rail to one side, the mainbody is pushed to move from a first position (or open position) of thechamber to a second position (or closed position), whereby the secondoperation board or the arm section thereof is synchronously driven tomove the second oblique rail to the other side.

The present invention can be best understood through the followingdescription and accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the present invention, showing that themain body is assembled with the base seat and the first and secondoperation boards and the main body is positioned in the first positionof the chamber of the base seat;

FIG. 2 is a perspective exploded view of the present invention accordingto FIG. 1 , showing the structures of the main body, the base seat, thefirst and second operation boards and the restriction sections disposedon the main body;

FIG. 3 is a plane view of the present invention according to FIG. 1 ,showing that the first and second operation boards are positioned in theopen position;

FIG. 4 is a perspective view of the operation of the present invention,showing that the first and second operation boards are moved from theopen position to the closed position and the main body is moved from thefirst position to the second position;

FIG. 5 is a sectional view of the present invention according to FIG. 4, in which the phantom lines show that the first and second operationboards are assembled with a case and a screen and the first and secondoperation boards synchronously rotate around a virtual axis;

FIG. 6 is another perspective view of the operation of the presentinvention, showing that the first and second operation boards arepositioned in the closed position and the main body is positioned in thesecond position; and

FIG. 7 is a sectional view according to FIG. 6 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1, 2 and 3 . The synchronous transmission pivotshaft device of the present invention includes an assembly of a mainbody 50, a first operation board 10 and a second operation board 20. Theupper section, upper side, bottom section, lower side, left end, leftside, right end, right side, etc. mentioned hereinafter are recited withthe direction of the drawings as the reference direction.

As shown in the drawings, the main body 50 is an arched plate body or acylindrical (or substantially semi-cylindrical) body. The main body 50has an open chamber 55 with an arched (cross-sectional) structure. Adiaphragm 56 is selectively disposed in a substantially middle positionof the chamber 55 to partition the chamber 55 into a first (arched)cavity 58 and a second (arched) cavity 59. In addition, the upper side(with reference to the drawings) of the main body 50 is formed with afirst notch 51 in communication with the first cavity 58. The lower sideof the main body 50 is formed with a second notch 52 in communicationwith the second cavity 59. The first notch 51 is positioned in aposition in adjacency to the diaphragm 56 (or in adjacency to the middleof the main body 50). The second notch 52 is positioned in a positiondistal from the diaphragm 56 (or distal from the middle of the main body50).

In this embodiment, multiple restriction sections are disposed orintegrally formed in the chamber 55. The restriction sections can beclassified into first restriction section 30 and second restrictionsection 40 respectively positioned in the first and second cavities 58,59. The first and second restriction sections 30, 40 are formed withmultiple block bodies with arched cross section. A first oblique rail 31is disposed in or defined by the first restriction section 30 incommunication with the first notch 51. A second oblique rail 42 isdisposed in or defined by the second restriction section 40 incommunication with the second notch 52.

In a preferred embodiment, the first and second oblique rails 31, 42respectively have the form of arched slot in adaptation to the arched(cross-sectional) structure of the main body 50 (or the chamber 55).

With the direction of the drawings as the reference direction, the firstoblique rail 31 obliquely extends from the upper side (or the firstnotch 51) to the lower side and left end of the main body 50.

The second oblique rail 42 obliquely extends from the upper side to thelower side and right end of the main body 50 (or the second notch 52).

As shown in FIGS. 1, 2 and 3 , the first and second operation boards 10,20 are disposed on the main body 50. The first operation board 10 has anarched arm section 11 protruding from the first operation board 10. Thesecond operation board 20 has an arched arm section 22 protruding fromthe second operation board 20. The arched arm sections 11, 22 of thefirst and second operation boards 10, 20 are respectively reciprocallymovably received in the first and second oblique rails 31, 42 of themain body 10. In addition, the arched arm sections 11, 22 of the firstand second operation boards 10, 20 respectively have connection ends 18,28 and free ends 19, 29.

In this embodiment, the arm section 11 of the first operation board 10obliquely extends from the connection end 18 to the free end 19 and theleft end (with reference to the drawings) corresponding to the firstoblique rail 31. The arm section 22 of the second operation board 20obliquely extends from the connection end 28 to the free end 29 and theleft end (with reference to the drawings) corresponding to the secondoblique rail 42.

As shown in the drawings, the main body 50 can be assembled and disposedon a base seat 60. The base seat 60 is an arched plate body or acylindrical (or substantially semi-cylindrical) body. The base seat 60has an open chamber 61 with an arched (cross-sectional) structure forreceiving the main body 50. The main body 50 is permitted toreciprocally move within the chamber 65 of the base seat 60. The upperside of the base seat 60 is formed with a first notch 61 correspondingto the first notch 51 of the main body. The lower side of the base seat60 is formed with a second notch 62 corresponding to the second notch 52of the main body.

In a preferred embodiment, an assembling section 54 in the form of anelongated raised structure (or elongated sunken structure) is disposedunder the bottom section of the main body 50. A guide section 64 in theform of an elongated sunken structure (or elongated raised structure) isdisposed in the chamber 65 of the base seat 60 corresponding to theassembling section 54 of the main body 50. Accordingly, when the mainbody 50 is mounted in the chamber 65 of the base seat, the assemblingsection 54 of the main body is assembled with the guide section 64 ofthe base seat, whereby the main body 50 can stably freely move withinthe chamber 65.

Please refer to FIG. 1 or 3 , which show that the main body 50 isassembled with the base seat 60 and the first and second operationboards 10, 20 (and the first and second restriction sections 30, 40).The assembling positions are such defined that the main body 50 ispositioned in a first position in the chamber 65 of the base seat andthe first and second operation boards 10, 20 are positioned in an openposition.

Please refer to FIGS. 4 and 5 . The phantom lines of FIG. 5 show thatthe first and second operation boards 10, 20 are assembled with a case70 and a screen 80. The screen 80 can be a flexible screen or anonflexible screen. When a user operates the case 70 (or the screen 80),the first and second operation boards 10, 20 are moved from the openposition to the closed position in a manner as follows:

-   1. The first operation board 10 or the arm section 11 of the first    operation board 10 and the second operation board 20 or the arm    section 22 of the second operation board 20 rotate around a virtual    axis C to respectively move along the first and second oblique rails    31, 42. Accordingly, the arm section 11 of the first operation board    10 is forced to gradually protrude from the first notch 51 (or the    first notch 61). At the same time, the main body 50 (or the first    and second restriction sections 30, 40) are driven to move from the    first position of the chamber 65 (or the right end of FIG. 4 ) to    the second position (or the left end of FIG. 4 ). It should be noted    that the virtual axis C is positioned at the center of the motional    range (or rotational range) of the arm section 11 of the first    operation board 10 and the arm section 22 of the second operation    board 20.-   2. In response to the move of the second restriction section 40, the    second oblique rail 42 synchronously drives the arm section 22 of    the second operation board 20 to gradually protrude from the second    notch 52 (or the second notch 62).

Please now refer to FIGS. 6 and 7 . When the first and second operationboards 10, 20 (or the case 70 and the screen 80) reach the closedposition, the main body 50 also reaches the second position from thefirst position of the chamber 65. Accordingly, the first and secondoperation boards 10, 20 (or the case 70 and the screen 80) can be openedand closed.

It should be noted that the first and second oblique rails 31, 42 arecurved and arranged along the virtual axis C. Also, the archedstructures (or the curvature) of the arm section 11 of the firstoperation board 10 and the arm section 22 of the second operation board20 are identical to the curvature of the first and second oblique rails31, 42.

To speak representatively, in condition that the requirement forlightweight and thin (or simplified) design of the electronic apparatusis satisfied, in comparison with the conventional pivot shaft device,the synchronous transmission pivot shaft device of the present inventionhas the following advantages:

-   1. The assembling structures of the main body 50 and the first and    second operation boards 10, 20 or base seat 60 have been redesigned    to form a single-shaft structure capable of synchronously rotating    and/or moving. For example, the first and second restriction    sections 30, 40 are disposed on the main body 10 to form the first    and second oblique rails 31, 42. The first and second operation    boards 10, 20 are respectively formed with the arched protruding arm    sections 11, 22, which can reciprocally move along the first and    second oblique rails 31, 42. Also, the main body 50 can move between    the first and second positions in the chamber 65 of the base seat.    These are obviously different from the structural form of the    conventional dual-shaft pivot shaft device.-   2. The assembling structures of the main body 50 and the first and    second operation boards 10, 20 or the base seat 60 and the flexible    screen 80 are able to achieve a beautiful appearance of the entire    electronic apparatus and provide a simplified and beautified visual    effect, whereby the shortcoming of the conventional dual-shaft pivot    shaft device that the components have larger volume to occupy more    (gap/motional) space. Moreover, the shortcomings of the conventional    dual-shaft pivot shaft device that the structure is unbeneficial to    the power transmission to cause idling travel and the cooperative    form is more complicated and it is troublesome to manufacture and    assemble the components and the assembling tolerance is large and    the cost is high are obviously improved.

In conclusion, the synchronous transmission pivot shaft device of thepresent invention is effective and different from the conventionaldual-shaft pivot shaft device in space form. The synchronoustransmission pivot shaft device of the present invention is inventive,greatly advanced and advantageous over the conventional dual-shaft pivotshaft device.

The above embodiments are only used to illustrate the present invention,not intended to limit the scope thereof. Many modifications of the aboveembodiments can be made without departing from the spirit of the presentinvention.

What is claimed is:
 1. A synchronous transmission pivot shaft devicecomprising: an assembly of a main body (50), a first operation board(10) and a second operation board (20) disposed on the main body (50),the main body (50) being an arched plate body and having a chamber (55),a first oblique rail (31) and a second oblique rail (42) positioned onthe chamber (55), the chamber (55) being an open chamber with an archedcross-sectional structure, an upper side of the main body (50) beingformed with a first notch (51), a lower side of the main body (50) beingformed with a second notch (52), the first notch (51) being positionedin a position in adjacency to a middle of the main body (50), the secondnotch (52) being positioned in a position distal from the middle of themain body (50), the first operation board (10) having a protruding armsection (11), the second operation board (20) having a protruding armsection (22), the arm section (11) of the first operation board (10) andthe arm section (22) of the second operation board (20) respectivelyhaving connection ends (18), (28) and free ends (19), (29), the armsection (11) of the first operation board (10) and the arm section (22)of the second operation board (20) being respectively received in thefirst oblique rail (31) and the second oblique rail (42), whereby whenthe first operation board (10) and the second operation board (20) move,the arm section (11) of the first operation board (10) and the armsection (22) of the second operation board (20) respectivelysynchronously move along the first oblique rail (31) and the secondoblique rail (42), a diaphragm (56) being in a middle position of thechamber (55) to partition the chamber (55) into a first cavity (58) anda second cavity (59), the first cavity (58) being in communication withthe first notch (51), the second cavity (59) being in communication withthe second notch (52).
 2. The synchronous transmission pivot shaftdevice as claimed in claim 1, wherein the first oblique rail (31) andthe second oblique rail (42) respectively have the form of arched slot,the first oblique rail (31) obliquely extending from an upper side to alower side and left end of the main body (50), the second oblique rail(42) obliquely extending from the upper side to the lower side and rightend of the main body (50), the arm section (11) of the first operationboard (10) obliquely extending from the connection end (18) to the freeend (19) and the left end to form an arched protruding structure, thearm section (22) of the second operation board (20) obliquely extendingfrom the connection end (28) to the free end (29) and the left end toform an arched protruding structure, the curvature of the archedstructures of the arm section (11) of the first operation board (10) andthe arm section (22) of the second operation board (20) being equal tothe curvature of the first oblique rail (31) and the curvature of thesecond oblique rail (42).
 3. A synchronous transmission pivot shaftdevice, comprising: an assembly of a main body (50), a first operationboard (10) and a second operation board (20) disposed on the main body(50), the main body (50) having a chamber (55), a first oblique rail(31) and a second oblique rail (42) positioned on the chamber (55), thefirst operation board (10) having a protruding arm section (11), thesecond operation board (20) having a protruding arm section (22), thearm section (11) of the first operation board (10) and the arm section(22) of the second operation board (20) respectively having connectionends (18), (28) and free ends (19), (29), the arm section (11) of thefirst operation board (10) and the arm section (22) of the secondoperation board (20) being respectively received in the first obliquerail (31) and the second oblique rail (42), whereby when the firstoperation board (10) and the second operation board (20) move, the armsection (11) of the first operation board (10) and the arm section (22)of the second operation board (20) respectively synchronously move alongthe first oblique rail (31) and the second oblique rail (42), whereinmultiple restriction sections are disposed in the chamber (55), therestriction sections being block bodies with arched cross section, therestriction sections being classified into first restriction section(30) and second restriction section (40), the first restriction section(30) defining the first oblique rail (31), the second restrictionsection (40) defining the second oblique rail (42).
 4. The synchronoustransmission pivot shaft device as claimed in claim 2, wherein multiplerestriction sections are disposed in the chamber (55), the restrictionsections being block bodies with arched cross section, the restrictionsections being classified into first restriction section (30) and secondrestriction section (40), the first restriction section (30) definingthe first oblique rail (31), the second restriction section (40)defining the second oblique rail (42).
 5. The synchronous transmissionpivot shaft device as claimed in claim 1, wherein multiple restrictionsections are disposed in the chamber (55), the restriction sectionsbeing block bodies with arched cross section, the restriction sectionsbeing classified into first restriction section (30) and secondrestriction section (40) respectively positioned in the first cavity(58) and the second cavity (59), the first restriction section (30)defining the first oblique rail (31) in communication with the firstnotch (51), the second restriction section (40) defining the secondoblique rail (42) in communication with the second notch (52).
 6. Thesynchronous transmission pivot shaft device as claimed in claim 4,wherein, the first restriction section (30) defining the first obliquerail (31) is in communication with the first notch (51), and the secondoblique rail (42) is in communication with the second notch (52).
 7. Asynchronous transmission pivot shaft device, comprising: an assembly ofa main body (50), a first operation board (10) and a second operationboard (20) disposed on the main body (50), the main body (50) having achamber (55), a first oblique rail (31) and a second oblique rail (42)positioned on the chamber (55), the first operation board (10) having aprotruding arm section (11), the second operation board (20) having aprotruding arm section (22), the arm section (11) of the first operationboard (10) and the arm section (22) of the second operation board (20)respectively having connection ends (18), (28) and free ends (19), (29),the arm section (11) of the first operation board (10) and the armsection (22) of the second operation board (20) being respectivelyreceived in the first oblique rail (31) and the second oblique rail(42), whereby when the first operation board (10) and the secondoperation board (20) move, the arm section (11) of the first operationboard (10) and the arm section (22) of the second operation board (20)respectively synchronously move along the first oblique rail (31) andthe second oblique rail (42), wherein the main body (50) is assembledand disposed on a base seat (60), the base seat (60) being an archedplate body having an open chamber (61) with an arched cross-sectionalstructure, the main body (50) being permitted to reciprocally movewithin the chamber (65) of the base seat (60), when the arm section (11)of the first operation board (10) rotates along the first oblique rail(31) to one side of the main body (50), the main body (50) being pushedto move from a first position of the chamber (65) to a second position,whereby the arm section (22) of the second operation board (20) issynchronously driven to rotate along the second oblique rail (42) to theother side of the main body (50), an upper side of the base seat (60)being formed with a first notch (61), a lower side of the base seat (60)being formed with a second notch (62), an assembling section (54) beingdisposed under the bottom section of the main body (50), the assemblingsection (54) being in the form of an elongated raised structure or anelongated sunken structure, a guide section (64) being disposed in thechamber (65) of the base seat (60), the guide section (64) being in theform of an elongated sunken structure or an elongated raised structure.8. The synchronous transmission pivot shaft device as claimed in claim2, wherein the main body (50) is assembled and disposed on a base seat(60), the base seat (60) being an arched plate body having an openchamber (61) with an arched cross-sectional structure, the main body(50) being permitted to reciprocally move within the chamber (65) of thebase seat (60), when the arm section (11) of the first operation board(10) rotates along the first oblique rail (31) to one side of the mainbody (50), the main body (50) being pushed to move from a first positionof the chamber (65) to a second position, whereby the arm section (22)of the second operation board (20) is synchronously driven to rotatealong the second oblique rail (42) to the other side of the main body(50), an upper side of the base seat (60) being formed with a firstnotch (61), a lower side of the base seat (60) being formed with asecond notch (62), an assembling section (54) being disposed under thebottom section of the main body (50), the assembling section (54) beingin the form of an elongated raised structure or an elongated sunkenstructure, a guide section (64) being disposed in the chamber (65) ofthe base seat (60), the guide section (64) being in the form of anelongated sunken structure or an elongated raised structure.
 9. Thesynchronous transmission pivot shaft device as claimed in claim 1,wherein the main body (50) is assembled and disposed on a base seat(60), the base seat (60) being an arched plate body having an openchamber (61) with an arched cross-sectional structure, the main body(50) being permitted to reciprocally move within the chamber (65) of thebase seat (60), when the arm section (11) of the first operation board(10) rotates along the first oblique rail (31) to one side of the mainbody (50), the main body (50) being pushed to move from a first positionof the chamber (65) to a second position, whereby the arm section (22)of the second operation board (20) is synchronously driven to rotatealong the second oblique rail (42) to the other side of the main body(50), an upper side of the base seat (60) being formed with a firstnotch (61) corresponding to the first notch (51) of the main body, alower side of the base seat (60) being formed with a second notch (62)corresponding to the second notch (52) of the main body, an assemblingsection (54) being disposed under the bottom section of the main body(50), the assembling section (54) being in the form of an elongatedraised structure or an elongated sunken structure, a guide section (64)being disposed in the chamber (65) of the base seat (60), the guidesection (64) being in the form of an elongated sunken structure or anelongated raised structure.
 10. The synchronous transmission pivot shaftdevice as claimed in claim 3, wherein the main body (50) is assembledand disposed on a base seat (60), the base seat (60) being an archedplate body having an open chamber (61) with an arched cross-sectionalstructure, the main body (50) being permitted to reciprocally movewithin the chamber (65) of the base seat (60), when the arm section (11)of the first operation board (10) rotates along the first oblique rail(31) to one side of the main body (50), the main body (50) being pushedto move from a first position of the chamber (65) to a second position,whereby the arm section (22) of the second operation board (20) issynchronously driven to rotate along the second oblique rail (42) to theother side of the main body (50), an upper side of the base seat (60)being formed with a first notch (61), a lower side of the base seat (60)being formed with a second notch (62), an assembling section (54) beingdisposed under the bottom section of the main body (50), the assemblingsection (54) being in the form of an elongated raised structure or anelongated sunken structure, a guide section (64) being disposed in thechamber (65) of the base seat (60), the guide section (64) being in theform of an elongated sunken structure or an elongated raised structure.11. The synchronous transmission pivot shaft device as claimed in claim4, wherein the main body (50) is assembled and disposed on a base seat(60), the base seat (60) being an arched plate body having an openchamber (61) with an arched cross-sectional structure, the main body(50) being permitted to reciprocally move within the chamber (65) of thebase seat (60), when the arm section (11) of the first operation board(10) rotates along the first oblique rail (31) to one side of the mainbody (50), the main body (50) being pushed to move from a first positionof the chamber (65) to a second position, whereby the arm section (22)of the second operation board (20) is synchronously driven to rotatealong the second oblique rail (42) to the other side of the main body(50), an upper side of the base seat (60) being formed with a firstnotch (61), a lower side of the base seat (60) being formed with asecond notch (62), an assembling section (54) being disposed under thebottom section of the main body (50), the assembling section (54) beingin the form of an elongated raised structure or an elongated sunkenstructure, a guide section (64) being disposed in the chamber (65) ofthe base seat (60), the guide section (64) being in the form of anelongated sunken structure or an elongated raised structure.
 12. Thesynchronous transmission pivot shaft device as claimed in claim 5,wherein the main body (50) is assembled and disposed on a base seat(60), the base seat (60) being an arched plate body having an openchamber (61) with an arched cross-sectional structure, the main body(50) being permitted to reciprocally move within the chamber (65) of thebase seat (60), when the arm section (11) of the first operation board(10) rotates along the first oblique rail (31) to one side of the mainbody (50), the main body (50) being pushed to move from a first positionof the chamber (65) to a second position, whereby the arm section (22)of the second operation board (20) is synchronously driven to rotatealong the second oblique rail (42) to the other side of the main body(50), an upper side of the base seat (60) being formed with a firstnotch (61) corresponding to the first notch (51) of the main body, alower side of the base seat (60) being formed with a second notch (62)corresponding to the second notch (52) of the main body, an assemblingsection (54) being disposed under the bottom section of the main body(50), the assembling section (54) being in the form of an elongatedraised structure or an elongated sunken structure, a guide section (64)being disposed in the chamber (65) of the base seat (60), the guidesection (64) being in the form of an elongated sunken structure or anelongated raised structure.
 13. The synchronous transmission pivot shaftdevice as claimed in claim 1, wherein the first and second operationboards (10), (20) are assembled with a case (70) and a screen (80), thearm section (11) of the first operation board (10) and the arm section(22) of the second operation board (20) move around a virtual axis (C),the virtual axis (C) is positioned at a center of the motional range ofthe arm section (11) of the first operation board (10) and the armsection (22) of the second operation board (20).
 14. The synchronoustransmission pivot shaft device as claimed in claim 2, wherein the firstand second operation boards (10), (20) are assembled with a case (70)and a screen (80), the arm section (11) of the first operation board(10) and the arm section (22) of the second operation board (20) movearound a virtual axis (C), the virtual axis (C) is positioned at acenter of the motional range of the arm section (11) of the firstoperation board (10) and the arm section (22) of the second operationboard (20).
 15. The synchronous transmission pivot shaft device asclaimed in claim 4, wherein the first and second operation boards (10),(20) are assembled with a case (70) and a screen (80), the arm section(11) of the first operation board (10) and the arm section (22) of thesecond operation board (20) move around a virtual axis (C), the virtualaxis (C) is positioned at a center of the motional range of the armsection (11) of the first operation board (10) and the arm section (22)of the second operation board (20).
 16. The synchronous transmissionpivot shaft device as claimed in claim 3, wherein the first and secondoperation boards (10), (20) are assembled with a case (70) and a screen(80), the arm section (11) of the first operation board (10) and the armsection (22) of the second operation board (20) move around a virtualaxis (C), the virtual axis (C) is positioned at a center of the motionalrange of the arm section (11) of the first operation board (10) and thearm section (22) of the second operation board (20).
 17. The synchronoustransmission pivot shaft device as claimed in claim 7, wherein the firstand second operation boards (10), (20) are assembled with a case (70)and a screen (80), the arm section (11) of the first operation board(10) and the arm section (22) of the second operation board (20) movearound a virtual axis (C), the virtual axis (C) is positioned at acenter of the motional range of the arm section (11) of the firstoperation board (10) and the arm section (22) of the second operationboard (20).
 18. The synchronous transmission pivot shaft device asclaimed in claim 12, wherein the first and second operation boards (10),(20) are assembled with a case (70) and a screen (80), the arm section(11) of the first operation board (10) and the arm section (22) of thesecond operation board (20) move around a virtual axis (C), the virtualaxis (C) is positioned at a center of the motional range of the armsection (11) of the first operation board (10) and the arm section (22)of the second operation board (20).